The invention relates to a method for feeding fine-grained matter to a concentrate burner or a matte burner of a suspension smelting furnace.
The invention also relates to an arrangement for feeding fine-grained matter to a concentrate burner or the matte burner of a suspension smelting furnace.
The invention also relates also to a controlling means for controlling feeding of fine-grained matter to a concentrate burner or a matte burner of a suspension smelting furnace in an arrangement for feeding fine-grained matter to a concentrate burner or a matte burner of a suspension smelting furnace.
Lost in weight feeding is based on measuring the mass of the material in a dosing bin and continuously calculating the change in mass (with respect to time) thus obtaining the mass flow rate from measured data. This mass flow rate can be used for continuously adjusting the speed of a screw conveyor in communication with the dosing bin to obtain an even flow of material to be fed from the screw conveyor. However, during filling of the dosing bin the mass flow calculation cannot be used due to sudden increase of mass in the dosing bin. The speed of the screw conveyor is therefore normally kept constant during filling of the dosing bin. After the filling is over, the screw conveyor is released and the feed rate is again adjusted based on the measured weight change as was made before the filling. A problem is that the optimum screw speed after the filling is totally different from the optimum screw speed prior to the filling, which leads to underfeeding or overfeeding of material after the filling. Especially in arrangements for feeding fine-grained matter to a concentrate burner or the matte burner of a suspension smelting furnace underfeeding or overfeeding fine-grained matter of has a negative effect on the process, because for example a too high feed rate leads to unburned fine-grained matter in the suspension smelting furnace.
Systems for feeding fine-grained matter to a concentrate burner or a matte burner of a suspension smelting furnace are for example presented in publication WO 2005/067366.